Concurrency::task_completion_event< void > Class Template Reference

The task_completion_event class allows you to delay the execution of a task until a condition is satisfied, or start a task in response to an external event. More...

#include <ppltasks.h>

Public Member Functions
bool	set () const
	Sets the task completion event. More...
template<typename _E >
	__declspec (noinline) bool set_exception(_E _Except) const
	__declspec (noinline) bool set_exception(std
	Propagates an exception to all tasks associated with this event. More...
void	_Cancel () const
	Cancel the task_completion_event. Any task created using this event will be marked as canceled if it has not already been set. More...
void	_Cancel (const std::shared_ptr< details::_ExceptionHolder > &_ExHolder) const
	Cancel the task_completion_event with the exception holder provided. Any task created using this event will be canceled with the same exception. More...
bool	_StoreException (const std::shared_ptr< details::_ExceptionHolder > &_ExHolder) const
	Method that stores an exception in the task completion event. This is used internally by when_any. Note, this does not cancel the task completion event. A task completion event with a stored exception can bet set() successfully. If it is canceled, it will cancel with the stored exception, if one is present. More...
void	_ClearStoredException () const
	Internal method that observe and clear the exception stored in the task completion event. This is used internally by when_any. More...
bool	_IsTriggered () const
	Test whether current event has been either Set, or Canceled. More...

Private Member Functions
void	_RegisterTask (details::_Task_ptr< details::_Unit_type >::_Type _TaskParam)
	Register a task with this event. This function is called when a task is constructed using a task_completion_event. More...

Private Attributes
task_completion_event< details::_Unit_type >	_M_unitEvent

Friends
template<typename _Ty >
class	task

Detailed Description

template<>
class Concurrency::task_completion_event< void >

The task_completion_event class allows you to delay the execution of a task until a condition is satisfied, or start a task in response to an external event.

Use a task created from a task completion event when your scenario requires you to create a task that will complete, and thereby have its continuations scheduled for execution, at some point in the future. The task_completion_event must have the same type as the task you create, and calling the set method on the task completion event with a value of that type will cause the associated task to complete, and provide that value as a result to its continuations.

If the task completion event is never signaled, any tasks created from it will be canceled when it is destructed.

task_completion_event behaves like a smart pointer, and should be passed by value.

See also

task Class

Member Function Documentation

template<typename _E >

Concurrency::task_completion_event< void >::__declspec ( noinline  ) const

inline

    {
        return _M_unitEvent._Cancel(std::make_exception_ptr(_Except), _CAPTURE_CALLSTACK());
    }

Concurrency::task_completion_event< void >::__declspec ( noinline  )

inline

Propagates an exception to all tasks associated with this event.

The exception_ptr that indicates the exception to set this event with.

    {
        // It is important that _CAPTURE_CALLSTACK() evaluates to the instruction after the call instruction for set_exception.
        return _M_unitEvent._Cancel(_ExceptionPtr, _CAPTURE_CALLSTACK());
    }

void Concurrency::task_completion_event< void >::_Cancel ( ) const

inline

Cancel the task_completion_event. Any task created using this event will be marked as canceled if it has not already been set.

    {
        _M_unitEvent._Cancel();
    }

void Concurrency::task_completion_event< void >::_Cancel ( const std::shared_ptr< details::_ExceptionHolder > &  _ExHolder ) const

inline

Cancel the task_completion_event with the exception holder provided. Any task created using this event will be canceled with the same exception.

    {
        _M_unitEvent._Cancel(_ExHolder);
    }

void Concurrency::task_completion_event< void >::_ClearStoredException ( ) const

inline

Internal method that observe and clear the exception stored in the task completion event. This is used internally by when_any.

    {
        _M_unitEvent._ClearStoredException();
    }

bool Concurrency::task_completion_event< void >::_IsTriggered ( ) const

inline

Test whether current event has been either Set, or Canceled.

    {
        return _M_unitEvent._IsTriggered();
    }

void Concurrency::task_completion_event< void >::_RegisterTask ( details::_Task_ptr< details::_Unit_type >::_Type  _TaskParam )

inlineprivate

Register a task with this event. This function is called when a task is constructed using a task_completion_event.

    {
        _M_unitEvent._RegisterTask(_TaskParam);
    }

bool Concurrency::task_completion_event< void >::_StoreException ( const std::shared_ptr< details::_ExceptionHolder > &  _ExHolder ) const

inline

Method that stores an exception in the task completion event. This is used internally by when_any. Note, this does not cancel the task completion event. A task completion event with a stored exception can bet set() successfully. If it is canceled, it will cancel with the stored exception, if one is present.

    {
        return _M_unitEvent._StoreException(_ExHolder);
    }

bool Concurrency::task_completion_event< void >::set ( ) const

inline

Sets the task completion event.

Returns

The method returns true if it was successful in setting the event. It returns false if the event is already set.

In the presence of multiple or concurrent calls to set, only the first call will succeed and its result (if any) will be stored in the task completion event. The remaining sets are ignored and the method will return false. When you set a task completion event, all the tasks created from that event will immediately complete, and its continuations, if any, will be scheduled. Task completion objects that have a _ResultType other than void will pass the value to their continuations.

    {
        return _M_unitEvent.set(details::_Unit_type());
    }

Friends And Related Function Documentation

template<typename _Ty >

friend class task

friend

Member Data Documentation

task_completion_event<details::_Unit_type> Concurrency::task_completion_event< void >::_M_unitEvent

private

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The documentation for this class was generated from the following file:

• VS2017/inc/ppltasks.h